1. Field of the Invention
This invention relates to aqueous cationic bituminous emulsions as mixing-grade emulsions. More particularly, it relates to oil-in-water-type cationic bituminous emulsions having improved mechanical stability emulsified with quaternary amines formed from the reaction of an alkyl phenol, epichlorohydrin and trimethylamine as the cation active emulsifier.
Mixing-grade oil-in-water bituminous emulsions, in which asphalt or similar bituminous material is emulsified in water by conventional emulsifiers, are extensively used to coat loose aggregate, such as stone, gravel and the like, in the construction and surfacing of roads, parking lots and other applications. The mixing-grade oil-in-water bituminous emulsions, which are employed to prepare the aggregate-containing mixes, must, therefore, be specially formulated to permit easy handling and ready application. The emulsions must remain stable (not set on initial contact) on being mixed with the aggregate; but once applied to the surface being paved or constructed, the emulsion should dehydrate satisfactorily at a predetermined rate (e.g., rapid set, medium set, or slow set, depending upon the use) and should display thorough penetration and firm adhesion of the bituminous binder to the aggregate.
2. The Prior Art
Cationic bituminous emulsions have come into use and obviate many of the disadvantages of the earlier used anionic emulsions. Cationic bituminous emulsions, e.g., asphalt-in-water emulsions, are formed by agitation of melted asphalt in water with the aid of cation-active emulsifiers which are either dissolved in the water employed for emulsification, or are dispersed in the asphalt phase before the emulsification, or yet emulsification may be carried out in situ. In contract to the anionic emulsions, bituminous emulsions formulated using cationic emulsifiers do not "set" in the same manner as anionic emulsions, but rather the bituminous material is deposited on the surface of the aggregate from the emulsion due to the attraction of polar charges between the bituminous droplets and negatively charged aggregate surfaces. Thus, cationic bituminous emulsions deposit more rapidly than the anionic bituminous emulsions on the aggregate surfaces and are bonded to the aggregate by the electrostatic action at the interface of the bitumen and the aggregative material. Control of the setting action of cationic bituminous emulsions is of considerable importance in road building and other applications. Due to the charge attraction mechanism, the rapidity of deposition of bituminous materials from the cationic emulsion is closely related to the generally negatively charged surface of the aggregate or filler material. While a specific cationic bituminous emulsion might provide suitable properties for use in conjunction with some aggregates, the same cationic emulsion may not exhibit suitable properties with others; thus, the ability to attain control of set times and coating characteristic is quite advantageous in obtaining an emulsion having wide applicability.
With the change from anionic asphalt emulsions to cationic asphalt emulsions several attempts have been set forth in the prior art for providing satisfactory cationic aqueous bituminous emulsions. Among those disclosed is U.S. Pat. No. 3,126,350 to Borgfeldt which discloses as a cationic emulsifier, a lignin amine product. Gzemski et al. in U.S. Pat. No. 3,518,101 disclose an emulsifier for oil-in-water emulsions which includes a diamine. Subsequently, other amines were disclosed in the prior art as cationic emulsifiers, such as those mono-quaternary and/or di-quaternary ammonium emulsifiers disclosed in U.S. Pat. No. 3,764,359 to Dybalski for slurry seal formulations. This list is intended to be exemplary only and does not represent the state of the art.
Therefore, it is a general object of this invention to provide a mixing-grade, oil-in-water bituminous emulsion.
Another object of this invention is to provide a cationic bituminous emulsion for mixing with aggregates whose coating characteristics and set time can be varied.
A further object of this invention is to provide a cationic quaternary amine emulsifier for bituminous emulsions for an aggregate mixture in which the rate of deposit after being applied to the surface to be treated may be controlled by the amount of emulsifier added and is workable for a period of time long enough to enable application in slurry form.
Still another object of this invention is to provide a new cationic quaternary amine emulsifier.
Other objects, features, and advantages of this invention will be evident from the foregoing disclosure.